’used to’ in Postive and negative statements used to 的肯定和否定形式
‘used to’ in Questions used to 的疑问形式
‘usedto’in Positive and negative Statements used to的肯定和否定形式
used to + 动词不定式表示在过去的某个时间段的习惯性动作或状况，而且还用来强调这个习惯性动作或状况现在已经不再进行或者存在了的这个事实。
主语+used to + 动词原形……
否定句
didn’t used
主语 + [ used not to ] + 动词原形……
never used to
否定句可以用以下的三种方法来表示：
① I didn’t use to watch television as a child
② I used not to watch television as a child
⑶ I never used to watch television as a child.
①是最经常使用的形式。
②是作为书面语最一般的形式，但是在口语中并不常用。
⑶是在书面语和口语中都很常用的表达。这个形式的语序和句基本相同（主语和used to 之间只加副词），所以可能是最简单的。
当然我们也可以在句子里加入除了never以外的表示频度的其他副词来构成一个肯定句。
always
frequently
hardly
I { ever } used to watch television as a child.
often
rarely
sometimes
另外，我们还可以在下面两个形式的否定句中加入表示频度的副词：
I didn’t use to watch television often as a child.
I used not to watch television often as a child.
‘used to’ in Questions used to的疑问形式
Yes/No一般疑问句
Did +主语 + use to + 动词原形……?
简单回答
Yes, + 主语言+ did.
No. + 主语言+ didn’t.
Did you sue to watch television as a child?
-Yes, I did.
- No, I didn’t.
特殊疑问句
●询问的部分中句子的主语的时候，就会变成下面的形式：
疑问词（句）+ used to + 动词原形……？
Who used to live in this house? 谁过去常常住在这栋房子里？
Which brother used to visit you? 哪个兄弟过去常常来看你？
How many people used to sleep in each room/每个房间过去常常有多少人睡？
What sort of animals used to inhabit this area? 哪种动物曾栖居于此？
What used to happen at night? 过去夜里常常发生什么？
